net/netfilter/nf_nat_redirect.c

   1 /*
   2  * (C) 1999-2001 Paul `Rusty' Russell
   3  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   4  * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
  11  * NAT funded by Astaro.
  12  */
  13
  14 #include <linux/if.h>
  15 #include <linux/inetdevice.h>
  16 #include <linux/ip.h>
  17 #include <linux/kernel.h>
  18 #include <linux/netdevice.h>
  19 #include <linux/netfilter.h>
  20 #include <linux/types.h>
  21 #include <linux/netfilter_ipv4.h>
  22 #include <linux/netfilter_ipv6.h>
  23 #include <linux/netfilter/x_tables.h>
  24 #include <net/addrconf.h>
  25 #include <net/checksum.h>
  26 #include <net/protocol.h>
  27 #include <net/netfilter/nf_nat.h>
  28 #include <net/netfilter/nf_nat_redirect.h>
  29
  30 unsigned int
  31 nf_nat_redirect_ipv4(struct sk_buff *skb,
  32                      const struct nf_nat_ipv4_multi_range_compat *mr,
  33                      unsigned int hooknum)
  34 {
  35         struct nf_conn *ct;
  36         enum ip_conntrack_info ctinfo;
  37         __be32 newdst;
  38         struct nf_nat_range2 newrange;
  39
  40         WARN_ON(hooknum != NF_INET_PRE_ROUTING &&
  41                 hooknum != NF_INET_LOCAL_OUT);
  42
  43         ct = nf_ct_get(skb, &ctinfo);
  44         WARN_ON(!(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED)));
  45
  46         /* Local packets: make them go to loopback */
  47         if (hooknum == NF_INET_LOCAL_OUT) {
  48                 newdst = htonl(0x7F000001);
  49         } else {
  50                 struct in_device *indev;
  51                 struct in_ifaddr *ifa;
  52
  53                 newdst = 0;
  54
  55                 indev = __in_dev_get_rcu(skb->dev);
  56                 if (indev && indev->ifa_list) {
  57                         ifa = indev->ifa_list;
  58                         newdst = ifa->ifa_local;
  59                 }
  60
  61                 if (!newdst)
  62                         return NF_DROP;
  63         }
  64
  65         /* Transfer from original range. */
  66         memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
  67         memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
  68         newrange.flags       = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
  69         newrange.min_addr.ip = newdst;
  70         newrange.max_addr.ip = newdst;
  71         newrange.min_proto   = mr->range[0].min;
  72         newrange.max_proto   = mr->range[0].max;
  73
  74         /* Hand modified range to generic setup. */
  75         return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
  76 }
  77 EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4);
  78
  79 static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
  80
  81 unsigned int
  82 nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
  83                      unsigned int hooknum)
  84 {
  85         struct nf_nat_range2 newrange;
  86         struct in6_addr newdst;
  87         enum ip_conntrack_info ctinfo;
  88         struct nf_conn *ct;
  89
  90         ct = nf_ct_get(skb, &ctinfo);
  91         if (hooknum == NF_INET_LOCAL_OUT) {
  92                 newdst = loopback_addr;
  93         } else {
  94                 struct inet6_dev *idev;
  95                 struct inet6_ifaddr *ifa;
  96                 bool addr = false;
  97
  98                 idev = __in6_dev_get(skb->dev);
  99                 if (idev != NULL) {
 100                         read_lock_bh(&idev->lock);
 101                         list_for_each_entry(ifa, &idev->addr_list, if_list) {
 102                                 newdst = ifa->addr;
 103                                 addr = true;
 104                                 break;
 105                         }
 106                         read_unlock_bh(&idev->lock);
 107                 }
 108
 109                 if (!addr)
 110                         return NF_DROP;
 111         }
 112
 113         newrange.flags          = range->flags | NF_NAT_RANGE_MAP_IPS;
 114         newrange.min_addr.in6   = newdst;
 115         newrange.max_addr.in6   = newdst;
 116         newrange.min_proto      = range->min_proto;
 117         newrange.max_proto      = range->max_proto;
 118
 119         return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
 120 }
 121 EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6);